Cheese Fudge

1 cup butter
2 cups shredded Cheddar cheese
1/2 cup unsweetened cocoa
2 cups confectioners' sugar
1/2 teaspoon vanilla extract
1/2 teaspoon vinegar
1 cup nuts, if desired

Melt butter, then pour it over the cheese. Mix together until creamy. Add remaining ingredients. Mix well. Refrigerate. When cool, cut into squares.